Auger-type ice making apparatus with improved evaporator

ABSTRACT

An improved evaporator is provided for an ice making apparatus of the auger-type. The evaporator employs an evaporator body having spiral grooves cut or milled into its outer cylindrical surface and a cylindrical jacket disposed over the spiral groove formed on the outer cylindrical surface of the evaporator body, with the jacket being in interference-fit engagement against the groove of the evaporator body. The interference fit is formed by thermal expansion of the jacket prior to it being telescopically slid over the body, followed by a cooling-down of the jacket, by which it shrinks or compresses radially inwardly, to tightly seal against the outer periphery of the grooves, creating a sealed path for refrigerant flow, from inlet to outlet of the evaporator.

BACKGROUND OF THE INVENTION

[0001] This invention relates to auger-type ice making machines used ina commercial setting, which produce flaked or chipped ice. Ice is formedby water freezing on the inner wall of a hollow cylindrical freezingchamber. A rotatable ice auger, sized to enable the scraping of ice offthe inner surface of the freezing chamber conveys the flaked ice towardan axial end of the freezing chamber whereby the flaked ice iscompressed into a rigid mass of ice which is subsequently severed intodiscrete, generally uniform chunks of ice.

[0002] The present invention is directed toward a new and improvedauger-type ice making machine which has an improved evaporator.

[0003] The present invention is an improvement upon U.S. Pat. No.5,394,708, the complete disclosure of which is herein incorporated byreference.

SUMMARY OF THE INVENTION

[0004] This invention relates to an auger-type ice making apparatus ofthe type wherein ice is produced on the inner walls of a cylindricalfreezing chamber. A rotatable ice auger scrapes such walls producingflaked ice.

[0005] In accordance with the present invention, the evaporator of theauger-type ice making machine comprises a cylinder comprising anevaporator body of significant wall thickness, which has a continuousspiral groove cut (preferably milled) on its outer cylindrical surface.This spiral groove embodies the refrigerant flow canal. A secondcylinder comprises a jacket which is placed around the evaporator body.The jacket has an interference fit around the body and can only be slidinto place after it is thermally expanded. Once the jacket has beenexpanded and slid into place, it is cooled and, upon being cooled,undergoes a radial contraction, whereby the inner cylindrical surface ofthe jacket seals tightly against the outer diameter of the spiral grooveof the evaporator body, such that refrigerant will flow only along thespiral groove, confined outwardly of the spiral groove by the innercylindrical surface of the jacket. Refrigerant inlet and discharge portsare provided through the jacket.

[0006] This invention relates generally to an auger-type ice makingapparatus where flaked ice is created on the interior wall of acylindrical freezing chamber, scraped of the wall by an ice auger, andtransferred out of the chamber, through a discharge aperture, to adischarge line.

[0007] It is accordingly a general object of the present invention toprovide a new and improved auger-type ice making apparatus, with animproved evaporator.

[0008] It is another object of the present invention to provide a newand improved auger-type ice making apparatus which comprises anevaporator body having spiral grooves in its outer cylindrical surface,which grooves, together with the inner cylindrical surface of a jacketthat is first heated or otherwise thermally expanded, and then allowedto cool, shrinks radially inwardly to form an interference fit againstthe continuous spiral groove, such that refrigerant delivered into andout of the spiral groove is confined between the evaporator body and thejacket, so as to flow only along the spiral groove from the inletthereto, to the outlet thereof.

[0009] Other objects and advantages of the present invention will becomeapparent from the following description taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTIONS OF THE DRAWINGS

[0010]FIG. 1 is a schematic diagram of an ice making apparatus of theprior art.

[0011]FIG. 2 is an elevational view, partially broken away and shown inlongitudinal section, of the auger-type ice generating apparatusembodied on the system shown in FIG. 1.

[0012]FIG. 3 is a perspective view of the evaporator body and jacket ofthis invention, shown assembled at the left of FIG. 1, and shownlongitudinally exploded at the right of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0013] Referring now in detail to the drawings, wherein like referencenumerals indicate like elements throughout the several views, there isshown in FIGS. 1 and 2 an ice making apparatus in accordance with onepreferred embodiment of the prior art, of which the present invention isan improvement. The illustrated apparatus is shown generally ascomprising an auger-type ice generating apparatus 10, with a motor means26 to drive the ice generating apparatus 10, an input line for water 18from a water source 16 to be frozen, an outlet delivery line 12 fordelivery of chunks of ice to an ice retaining means 14, a refrigerationmeans comprising a compressor means 20, a condenser means 22, anexpansion valve 27, and evaporator 24 to supply refrigeration to the icegenerating means 10.

[0014] In operation of the ice maker according to the prior art,conventional refrigerant under pressure is sent from the compressormeans 20 via line 37 to the condenser means 22. The refrigerant isthereafter liquefied within the condenser means 22 and then passedthrough an expansion valve 27 to the evaporator 24. Evaporator 24, whichcompletely surrounds the ice making machine 10, boils the liquidrefrigerant under low pressure to extract heat from, and accordinglycool, the generally cylindrical ice freezing chamber. Evaporator 24additionally comprises an evaporator cover 29 which serves as aninsulator and protective cover. Water is supplied to the cylindricalfreezing chamber 30, which houses an ice auger 28, from a water source16 through water input line 18. A constant level of water 25 ismaintained in the freezing chamber. Water freezes on the inner wall 38of the freezing chamber 30 and is scraped off by means of the ice auger28.

[0015] The ice generating apparatus 10 according to the prior art isshown in greater detail in FIG. 2. The auger 28 is disposed verticallyin the interior of the freezing chamber 30 and is driven by shaft 44.Actuation of the motor means 26 results in a rotation of the auger 28which causes ice to be scraped off the inner wall 38 of the freezingchamber 30 in flaked form. The ice generating apparatus 10 includes awater inlet 32, formed on its lower end for receiving water from theinlet line 18, and an ice discharge 34, formed on the upper end fordelivering generated ice to the delivery line 12. Tubing 36 is alsoincluded, wrapped a plurality of times around the freeing chamber 30which defines the aforementioned evaporator 24. Evaporator 24 includesan inlet 33 for receiving the refrigerant from the expansion valve 27,and refrigerant vapor is passed out through an outlet 35, into outletline 54 where, as shown in FIG. 1, it is carried back to the compressormeans 20. The refrigerant extracts heat from the ice generatingapparatus 10 through the walls of freezing chamber 30 as it is passedthrough the evaporator 24. This causes some of the water containedwithin the freezing chamber 30 to freeze along the inner wall 38.

[0016] Auger 28 includes at least one coiled band of scrapers 42extending outward from the auger surface 56, in close proximity to theinner wall 38 of the freezing chamber 30. A drive shaft 44 connects tothe motor means 26 extending axially through the auger 28. Accordingly,as auger 28 is rotated, the scraper 42 shaves the ice formed on theinside walls 38, carrying it axially upward, in the form of slush, to becompacted against an annular compacting head 51.

[0017] As indicated above, the ice discharged through the discharge 34is sent via line 12 to the retaining means 14.

[0018] The use of a prior art evaporator that includes a wrapping ofcopper tubing around a cylindrical body is avoided. In accordance withthe prior art, such a copper tube, when brazed into a refrigerationcircuit, embodies the refrigerant flow canal of the evaporator.Attachment of the wrapped tube to the cylinder body is typicallyaccomplished by using a solder to bond them together. Often the wrappedassembly is dipped into a molten solder tank, allowing the solder toflow underneath and in between the copper tubing wrap. Such attachmentand subsequent insulation of the copper tubing wrap is a labor andprocess intensive endeavor. Additionally, evaporator performance andreliability depend on proper execution of the process because propercopper tube attachment is critical to ensure heat transfer from thewater within the evaporator to the refrigerant in order to freeze thewater, and it is vital that moisture be sealed out of the wrapped tubingarea of the evaporator assembly. If moisture is not sealed out and iceis formed between the copper tubing wrap and body, the subsequentexpansion and contraction due to freeze/thaw operation cycles may causecopper wrap separation and/or structural failure of the body itself.Generally the solder is used not only to bond the copper tube to thebody, but also acts as a moisture seal.

[0019] The problems associated with a wrapped and dipped evaporatormanufacturing process are numerous. For example, the wrapped tube maytend to distort as it is wrapped around the body, creating voids and airgaps that can harm performance. Furthermore, the wrap may tend to“spring” when the assembly is removed from the wrapping apparatus, sothe ends of the copper tube must be attached, typically via spotwelding, to the body, in order to counter such tendency to “spring”. Ifthe wrap is too tight, the solder will not flow properly. If the wrap istoo loose, the heat transfer may not be appropriate. Furthermore, solderadhesion is problematic, especially when the body is stainless steel. Ata minimum the body needs to be fluxed in an acid prior to dipping itinto a solder, if not actually pre-tinned prior to wrapping. It has beenfound that solder adhesion is critical to evaporator performance.Additionally, in a wrap assembly, the assembly must be pre-heated priorto solder dipping, in order to avoid dangerous eruption of the soldertank which could occur should a cold assembly be introduced into moltensolder. Furthermore, solder must never flow to the interior of theevaporator body, because of the lead content of the solder, but sealingof the ends of the evaporator during the dipping process has been foundto problematic. Additionally, attaching insulation to the exterior ofthe dipped assembly is difficult due to the uneven outer surface.Typically, a shell is placed around the assembly, and a foam-in-placeoperation is performed, with the intent of having the insulation flowinto the voids, further sealing the dipped area from moisture.

[0020] Referring now to FIG. 3, it will be seen that the improvedevaporator 125 of the present invention is generally designated in placeof the evaporator 24 of FIGS. 1 and 2, and comprises an evaporator body130 and a jacket 131.

[0021] The evaporator body 130 has an inner cylindrical wall 138 and, onits outer cylindrical surface, a spiral groove 140, which is milled, orotherwise cut into the exterior cylindrical surface of the evaporatorbody 130 to define a spiral groove 140 from a location above the lowerend 141 of the body 130, to a location below the upper end 142 thereof.At opposite ends of the spiral groove 140 there are circumferentialgrooves 143, 144.

[0022] A refrigerant inlet port 145 is provided in the cylindricaljacket 125, fed by the refrigerant delivery line 39 of FIG. 1, with therefrigerant being carried off via refrigerant discharge port 146, to therefrigerant outlet line 54 of FIG. 1.

[0023] It will be apparent that, except for the evaporator construction,the ice making apparatus of this invention is in accordance with theapparatus of FIGS. 1 and 2, with the evaporator of FIGS. 1 and 2 beingreplaced by the evaporator construction of FIG. 3.

[0024] The cylindrical jacket 131 has an interference fit against theouter peripheral edges 147 of the spiral cut 140, to seal refrigerantthat enters via port 145, to remain within the spiral groove 140, fromits inlet location 145, to its discharge location 146.

[0025] The manner in which the interference fit is achieved is byheating the jacket 131 prior to sliding it into place over the body 130of the evaporator 125, whereby the jacket 125 thermally expands to agreater diameter, or outwardly, in the radial direction. After thejacket 125 is in place over the body 130, it is cooled and shrinks orreduces in diameter, or in a radial direction, until the innercylindrical surface 148 thereof tightly engages against the outerperipheral edges 147 of the continuous helical or spiral groove 140formed on the outer surface of the body, whereby it tightly sealsthereagainst.

[0026] Thus, refrigerant entering via inlet port 145, intocircumferential groove 143, is caused to pass along the helical grooveuntil it reaches the upper circumferential groove 144, whereby it canexit the evaporator via exit port 146, to line 54, and back to thecompressor 20.

[0027] An auger 28 disposed inside the auger body thus, as set forth inthe description above with respect to FIGS. 1 and 2, scrapes ice fromthe inner cylindrical wall 138 of the body, delivering the same upwardthrough the evaporator, to discharge via ice discharge port 134, to anice delivery line 12, back to an ice retaining means 14.

[0028] The jacket 131 is welded to the evaporator body 130 at upper andlower ends thereof, at locations 150 and 151, as shown in FIG. 3, toensure proper refrigerant sealing within the groove 140.

[0029] It will be seen that, in accordance with this invention, themanufacturing process for forming an evaporator is greatly simplified,in that it is not necessary to use a wrapped tube construction, and theproblems associated with a wrapped tube construction are therebyavoided. Moreover, the spiral groove that is formed in accordance withthis invention is no longer subjected to variations that are inherent ina wrapped dipped tube construction. Additionally, with the presentinvention moisture can no longer affect the integrity of the refrigerantpath or evaporator structure. Additionally, in accordance with thepresent invention, more simplified forms of insulation can be used, forexample, a simple foam material can be fastened in place to insulate theevaporator. Additionally, by employing circumferential grooves at eachend of the body, the heat transfer between thick-walled ends of theevaporator and the spiral groove is minimized. Furthermore, by locatingthe refrigerant inlet and outlet ports 145 and 146 as disclosed hereinrelative to the spiral groove 140, refrigerant turbulence can beeffected to the highest degree, with minimal loss due to pressure drop.

[0030] It will be recognized by those skilled in the art that changesmay be made in the above described embodiments of the invention withoutdeparting from the broad inventive concepts thereof. It is understood,therefore, that this invention is not limited to the particularembodiments disclosed, but is intended to cover all modifications whichare within the scope and spirit of the invention as defined by theappended claims.

What is claimed is:
 1. An ice making apparatus comprising: (a) agenerally cylindrical and hollow freezing chamber; (b) a compacting headat an end of said freezing chamber; (c) a rotatable ice auger sized tofit into said freezing chamber whereby said auger scrapes ice formed onthe walls of said chamber and conveys the ice toward a discharge end ofsaid auger and said compacting head; (d) an evaporator comprising anevaporator body and a jacket; (e) the evaporator body having acontinuous generally spiral grove on its outer cylindrical surface,terminating in a radial outward edge; with the evaporator having arefrigerant inlet and refrigerant outlet. (f) the evaporator jacketbeing telescopically disposed over the spiral groove of the evaporatorbody and being in interference fit against the outward edge of thespiral groove, sealingly engaging the evaporator jacket against theevaporator body, whereby refrigerant entering into the groove issealingly trapped therein between a refrigerant inlet and a refrigerantoutlet.
 2. The apparatus of claim 1, wherein the evaporator bodyincludes a cylindrical groove at a lower end thereof and anothercylindrical groove at an upper end thereof, with the cylindrical groovebeing in respective communication with the refrigerant inlet andrefrigerant outlet.
 3. The apparatus of claim 1 wherein the jacket iswelded to the evaporator body at both upper and lower ends of theevaporator body.
 4. The apparatus of claim 1, wherein the spiral groovecomprises a helical groove.
 5. The apparatus of claim 1, wherein theinterference fit is obtained by a thermally expanded jacket that issubsequently cooled to effect the interference fit against the outwardedge of the spiral groove.
 6. The apparatus of claim 1, wherein thecompacting head is annular and is disposed normal to the axis of thefreezing chamber.
 7. A method of making an ice making apparatuscomprising: (a) providing a generally cylindrical and hollow freezingchamber; (b) providing a compacting head at an end of said freezingchamber; (c) providing a rotatable ice auger sized to fit into saidfreezing chamber and disposing the auger in the freezing chamber wherebysaid auger scrapes ice formed on the walls of said chamber and conveysthe ice toward a discharge end of said auger and said compacting head;(d) providing an evaporator comprising an evaporator body and a jacket;(e) providing on the evaporator body a continuous generally spiral groveon its outer cylindrical surface, terminating in a radial outward edge;and providing to the evaporator with a refrigerant inlet and refrigerantoutlet. (f) telescopically disposing the evaporator jacket over thespiral groove of the evaporator body to be in interference fit againstthe outward edge of the spiral groove and thereby sealingly engaging theevaporator jacket against the evaporator body, whereby refrigerantentering into the groove is sealingly trapped therein between therefrigerant inlet and the refrigerant outlet.
 8. The method of claim 7,including providing the evaporator body with a cylindrical groove at alower end thereof and another cylindrical groove at an upper endthereof, so that the cylindrical groove is in respective communicationwith the refrigerant inlet and refrigerant outlet.
 9. The method ofclaim 7, including the step of molding the jacket is welded to theevaporator body at both upper and lower ends of the evaporator body. 10.The method of claim 7, wherein the step of providing the spiral groovecomprises forming a helical groove.
 11. The method of claim 7, whereinthe interference fit is obtained by thermally expanding the jacket andsubsequently cooling the jacket to effect the interference fit againstthe outward edge of the spiral groove.
 12. The method of claim 6,wherein the step of providing a compacting head comprises the step ofproviding an annular compacting head, normal to the axis of the freezingchamber.